You can simply 'split up' a certain range. For example, if you set the standard type of grey gas giant from (0.00, 0.25) to (0.00, 0.15) and add Toty's gorgeous black-brown-red ones with StyleRange (0.15, 0.25), 60% of hot gas giants will be the standard ones and 40% will be the black-brown-red ones. You don't have to respect the boundaries between temperatures either: if you make a gas giant type have a StyleRange of (0.45, 0.55) it'll mean 20% of temperate gas giants and 20% of cool gas giants will have this style.

No, there's 4 ranges by standard, but adding more is no problem; the place between 0 and 1 where you place these just affects at what temperatures they show up. I've got about 20 gas giant styles by now, trust me it works.

Great idea, that's very useful, especially for gas giants where the names of each feature correspond to completely unrelated things on the planet. Though I've built up a decent idea of which parts of the planet each tag means, it required a lot of trial and error.